The ever increasing demand for electrical power and the attendant increase in peak load demands, particularly when considered in the light of current public resistance to the construction of new generating and transmission facilities, has created a serious problem of expanding severity to the electric utilities. One expedient that has been employed to reduce peak demand is to reduce the line voltage. Such however is basically undesirable for a number of practical reasons and is usually resorted to only in time of incipient emergency. Another expedient designed to ameliorate the above problem is the utilization of load management techniques to reduce peak demand by enabling the utility to directly control the ability of consumers to utilize certain electrical devices.
Load management control of consumer power consumption is a serious undertaking and, although simple in concept, is fraught with complex and practical problems. For example, not all loads are amenable to such control, both in the industrial consumer area and in the residential consumer area. In the latter area, load management has been effectively practiced in the control of residential water heaters and one suggested system therefore is described in U.S. Pat. No. 4,450,875. Power consumption by electric water heaters however is relatively small in terms of overall power quantities. Far greater amounts of power are consumed, for example, by residential electrical heating systems, such as electric resistance baseboard heating. Load management control of domestic electrical heating systems such as electric baseboard heating presents complex problems. Unlike water heater control, when control system failure results only in customer inconvenience, loss of system control for residential heating service can have potentially disastrous consequences including property damage and possible physical harm to the customer.
Electric space heating represents a significant electric load that, in most winter peaking utilities, has a major influence on the magnitude and timing of the electric system peak demand. Most electric home heating systems employ baseboard resistance heating elements and have separate control points, such as a line voltage thermostat in each room, and thus represent multiple heating systems within a single residence. At least two methods of automatic load control of baseboard resistance heating systems have been suggested, one being the installation of powerline carrier equipment to control the line voltage thermostats and the other being hard wiring of a low voltage control system onto an existing line voltage multiple control system. Both of these expedients involve excessive installation costs, which, for an average home installation, are economically impractical.